Herbicidal compositions comprising dimethenamid and bentazone

ABSTRACT

Co-application of dimethenamid with other herbicides provides improved herbicidal activity.

This application is a division of application Ser. No. 08/467,367, nowU.S. Pat. No. 5,721,191, filed Jun. 6, 1995, which is acontinuation-in-part of application Ser. No. 08/153,946, filed Nov. 16,1993 abandoned, which is a continuation of application Ser. No.08/019,386, filed Feb. 18, 1993, abandoned and a continuation-in-part ofapplication Ser. No. 08/152,066, filed Nov. 12, 1993 , abandoned whichis a continuation-in-part of application Ser. No. 08/019,933, filed Feb.19, 1993, abandoned and a continuation of application Ser. No.08/236,732, filed May 2, 1994 U.S. Pat. No. 5,877,115.

The present invention concerns a method of controlling undesired plantgrowth employing co-application of dimethenamid and at least one otherherbicide, herbicidal compositions comprising dimethenamid and at leastone other herbicide and the use of such compositions in controllingundesired plant growth.

Dimethenamid (FRONTIER®) whose chemical name is2-chloro-N-(2,4-dimethyl-3-thienyl)-N-(2-methoxy-1-methylethyl)-acetamide,processes for its production, herbicidal compositions containing it andits use as a herbicide are described in U.S. Pat. No. 4,666,502 thecontents of which are incorporated herein by reference. Dimethenamidconsists of 4 stereoisomers due to two chiral elements and can thus alsoexist in the form of the individual isomers as diastereomeric mixtures(1S, aRS (known as S-dimethenamid) and 1R, aRS (known asR-dimethenamid)) and as a racemic mixture (1RS, aRS). References hereinto dimethenamid refer to its various forms unless otherwise stated. Ofthe diastereomeric mixtures S-dimethenamid is preferred.

The term herbicides, as used herein, refers to compounds which combat orcontrol undesired plant growth. This class of compounds may be dividedinto sub-classes according to the primary type or mode of action theherbicide has on the plant. For example according to G. F. Warren ofPurdue University, Indiana, USA, herbicides can be classified as auxintransport inhibitors, growth regulator herbicides, photosynthesisinhibitors, pigment inhibitors, growth inhibitors, amino acid synthesisinhibitors, lipid biosynthesis inhibitors, cell wall biosynthesisinhibitors, rapid cell membrane disruptors as well as "miscellaneous"herbicides which do not come under one of the preceding categories.

It has now surprisingly been found that co-application of dimethenamidand at least one other herbicide results in better and in some caseslonger-lasting control of undesired plant growth. This synergisticeffect exhibits itself in a high degree of control at co-applicationrates which are significantly lower than the rate of each individualcompound required to obtain the same degree of control. Furthermore. atany given co-application rate the degree of control is higher than theadditive effect obtained for the individual components at the same rate.In some cases both speed of activity and level of control are enhancedand/or weeds can be controlled which are not controlled by eithercomponent at economical rates.

This synergistic effect allows for satisfactory control at reducedapplication rates for each component and even at levels which if appliedfor a particular component alone would give insufficient control.Additionally, longer residual control may be achieved. This provides forsignificant economic and environmental advantages in the use ofdimethenamid and the herbicide(s) used in combination therewith.

Co-application can be achieved using tank mixes of preformulatedindividual active ingredients, simultaneous or sequential (preferably1-2 days) application of such formulations or application ofpreformulated fixed pre-mix combinations of the individual activeingredients.

Examples of herbicides which may be used in combination withdimethenamid in accordance with the invention include

1. auxin transport inhibitors, e.g. naptalam

2. growth regulators, including 1) benzoic acids, e.g. dicamba; b)phenoxy acids i) acetic acid type, e.g. 2,4-D, MCPA, ii) propionic acidtype, e.g. 2,4-DP, MCPP, iii) butyric acid type, e.g. 2,4-DB, MCPB; c)picolinic acids and related compounds, e.g. picloram, triclopyr,fluroxypyr, clopyralid

3. photosynthesis inhibitors, including a) s-triazines i) chlorosubstituted, e.g. atrazine, simazine, cyanazine, ii) methoxysubstituted, e.g. prometon, iii) methylthio substituted, e.g. ametryn,prometryn; b) other triazines, e.g. hexazinone, metribuzin; c)substituted ureas, e.g. diuron, fluometuron, linuron, tebuthiuron,thidiazuron, forchlorfenuron; d) uracils, e.g. bromacil, terbacil; e)others, e.g. bentazon, desmedipham, pheninedipham, propanil, pyrazon,pyridate

4. pigment inhibitors, including a) pyridazinones, e.g. norflurazon; b)isoxazolones, e.g. clomazone; c) others, e.g. amitrole, fluridone

5. growth inhibitors, including a) mitotic disruptors i)dinitroanilines, e.g. trifluralin, prodiamine, benefin, ethalfluralin,isopropalin, oryzalin, pendimethalin; ii) others, e.g. DCPA, dithiopyr,thiazopyr, pronamide; b) inhibitors of shoots of emerging seedlings i)thiocarbamates, e.g. EPTC, butylate, cycloate, molinate, pebulate,thiobencarb, triallate, vernolate; c) inhibitors of roots only ofseedlings, e.g. bensulide, napropamide, siduron; d) inhibitors of rootsand shoots of seedlings, including chloroacetamides e.g. alachlor,acetochlor, metolachlor, diethatyl, propachlor, butachlor, pretilachlor,metazachlor, dimethachlor, and others e.g. cinmethylin

6. amino acid synthesis inhibitors, including a) glyphosate,glufosinate; b) sulfonylureas, e.g. rimsulfuron, metsulfuron,nicosulfuron, triasulfuron, primisulfuron, bensulfuron, chlorimuron,chlorsulfuron, sulfometuron, thifensulfuron, tribenuron,ethametsulfuron, triflusulfuron, clopyrasulfuron, pyrazasulfuron,prosulfuron (CGA-152005), halosulfuron, metsulfuron-methyl,chlorimuron-ethyl; c) sulfonamides, e.g. flumetsulam (a.k.a. DE498); d)imidazolinones, e.g. imazaquin, imazamethabenz, imazapyr, imazethapyr,imazmethapyr

7. lipid biosynthesis inhibitors, including a) cyclohexanediones, e.g.sethoxydim, clethodim; b) aryloxyphenoxys, e.g. fluazifop-(P-butyl),diclofop-methyl, haloxyfop-methyl, quizalofop; c) others e.g.fenoxaprop-ethyl

8. cell wall biosynthesis inhibitors, e.g. dichlobenil, isoxaben

9. rapid cell membrane disruptors, including a) bipyridiliums, e.g.paraquat, diquat; b) diphenyl ethers, e.g. acifluorfen, fomesafen,lactofen, oxyfluorfen; c) glutamine synthetase inhibitors, e.g.glufosinate; d) others, e.g. oxadiazon

10. miscellaneous, including a) carbamates, e.g. asulam; b) nitriles,e.g. bromoxynil, ioxynil; c) hydantocidin and derivatives, d) various,e.g. paclobutrazol, ethofumesate, quinclorac (a.k.a. BAS514),difenzoquat. endothall, fosamine, DSMA, MSMA

11. Others

a) triketones and diones of the type described in U.S. Pat. Nos.5,336,662 and 5,608,101 the contents of each of which are incorporatedherein by reference and in EP-A-338-992; EP-A-394-889; EP-A-506,967;EP-A-137,963; EP-A-186-118; EP-A-186-119; EP-A-186-120; EP-A-249-150;AND EP-A-336-898. Examples of such triketones and diones are sulcotrione(MIKADO®) whose chemical designation is2-(2-chloro-4-methanesulfonylbenzoyl)-1,3-cyclohexanedione:2-(4-methylsulfonyloxy-2-nitrobenzoyl)-4,4,6,6-tetramethyl-1,3-cyclohexanedione;3-(4-methylsulfonyloxy-2-nitrobenzoyl)-bicyclo3,2,1!octane-2,4-dione3-(4-methylsulfonyl-2-nitrobenzoyl)-bicyclo3,2,1!octane-2,4-dione;4-(4-chloro-2-nitrobenzoyl)-2,6,6-trimethyl-2H-1,2-oxazine-3,5(4H,6H)dione;4-(4-methylthio-2-nitrobenzoyl)-2,6,6-trimethyl-2H-1,2-oxazine-3,5(4H,6H)-dione;3-(4-methylthio-2-nitrobenzoyl)-bicyclo- 3,2,1!octane-2,4-dione;4-(2-nitro-4-trifluoromethoxybenzoyl)-2,6,6-trimethyl-2H-1,2-oxazine-3,5(4H,6H)-dione.

b) Compounds of the type described in U.S. Pat. No. 5,506,192EP-A-461,079; EP-A-549,524; EP-A-315,589 and PCT Appln. No. 91/10653;contents of which are incorporated herein by reference; including forexample 3-(4,6-dimethoxy-2-pyrimidinyl)hydroxymethyl!-N-methyl-2-pyridinecarboxamide;4,7-dichloro-3-(4,6-dimethoxy-2-pyrimidinyl)-3-hexanoyloxyphthalide; 3-(4,6-dimethoxy-2-pyrimidinyl)carbonyl!-N,N-dimethyl-2-pyridinecarboxamide; 3,6-dichloro-2-(4,6-dimethoxy-2-pyrimidinyl)carbonyl!benzoic acid; 6-chloro-2-(4,6-dimethoxy-2-pyrimidinyl)thio!benzoic acid (a.k.a. DPX-PE350 orpyrithiobac) and salts thereof.

The present invention therefore concerns a method of combatting orcontrolling undesired plant growth or otherwise regulating plant growthwhich comprises co-applying to a locus where such combatting or controlis desired an herbicidally or plant growth regulating effectiveaggregate amount of dimethenamid and at least one other herbicide.

Application rates for co-application will of course vary depending uponclimatic conditions, season, soil ecology, weeds to be combatted and thelike, however, successful results can be obtained e.g. with rates ofdimethenamid of 0.1 to 3.0 kg/ha, preferably 0.1 to 2.0 kg/ha,especially 0.25 to 1.5 kg/ha e.g. 0.9 to 1.5 kg/ha in co-applicationwith rates for partner herbicides which correspond to or aresignificantly lower than recommended for use thereof individually.

The suitability of specific co-applications for pre- or post-emergentuses and selectively will of course depend on the partners chosen.

The activity of dimethenamid is described in the above mentioned patentsand that of suitable herbicidal partners is described in the literatureor on commercially available forms thereof (cf also CROP PROTECTIONCHEMICALS REFERENCE, 9th edition (1993) Chemical & Pharmaceutical Press,New York, N.Y.; The Pesticide Manual, 9th edition (1991), British CropProtection Council, London; Ag Chem New Product Review, Ag ChemInformation Services, Indianapolis, Indiana; Farm Chemicals Handbook,1993 edition, Meister Publishing Company, Willoughby, Ohio and thelike).

The invention also provides herbicidal or plant growth regulatingcompositions comprising an herbicidally effective aggregate amount ofdimethenamid and at least one other herbicide.

Such compositions contain the active substances in association withagriculturally acceptable diluents. They may be employed in either solidor liquid forms e.g. in the form of a wettable powder or an emulsifiableconcentrate, incorporating conventional diluents. Such compositions maybe produced in conventional manner, e.g. by mixing the active ingredientwith a diluent and optionally other formulating ingredients such assurfactants and oils.

The term diluents as used herein means any liquid or solidagriculturally acceptable A. material which may be added to the activeconstituent to provide a more easily or improved applicable form, or toachieve a usable or desirable strength of activity. Examples of diluentsare talc, kaolin, diatomaceous earth, xylene, non-phytotoxic oils orwater.

Particular formulations, to be applied in spraying forms such as waterdispersible concentrates or wettable powders, may contain surfactantssuch as wetting and dispersing agents e.g. the condensation product offormaldehyde with naphthalene sulphonate, an alkylarylsulphonate, alignin sulphonate, a fatty alkyl sulphate, an ethoxylated alkylphenol oran ethoxylated fatty alcohol.

In general, the formulations include from 0.01 to 90% by weight ofactive agent(s) and from 0 to 20% by weight of agriculturally acceptablesurfactant the active agent consisting of dimethenamid and at least oneother herbicide. Concentrate forms of compositions generally containbetween about 2 and 90%. preferably between about 5 and 80% by weight ofactive agent. Application forms of formulation may for example containfrom 0.01 to 20% by weight of active agent.

When employing concurrent, immediately sequential or tank mixapplications the herbicide partner(s) can be employed in commerciallyavailable form if appropriate and at rates equivalent to or preferablybelow those recommended by the manufacturer or in the references citedabove. Dimethenamid can also be applied in commercially available form(e.g. as FRONTIER® herbicide) or as formulated e.g. as described in theabove-mentioned U.S. Pat. No. 4,666,502.

On co-application according to the present invention other compoundshaving biological activity, e.g. compounds having insecticidal orfungicidal activity, may also be included.

The preferred mode of application is tank mix prepared e.g. by addingdimethenamid to a tank containing the other herbicide partner and anappropriate surfactant or vice versa depending on the type of herbicidepartner chosen. It is advisable to consult labels of mixing partners andto conduct compatibility tests prior to mixing.

Depending on the choice of co-application partners both pre- andpost-emergence activity on a large range of broadleaf and grassy weedsmay be achieved. Examples of such weeds are

Agropyron repens--quackgrass

Brachiaria platyphylla--broadleaf signalgrass

Bromus spp--e.g. downybrome

Cenchrus ssp.--e.g. southern sandbur, sandbur, field sandbur

Dactyloctenium aegyptium--crowfootgrass

Digitaria spp--e.g. crabgrass, smooth crabgrass, large crabgrass

Echinochloa crus-galli--barnyardgrass

Eleusine indica--goosegrass

Eriochloa spp.--e.g. southwestern cupgrass, prairie cupgrass, woollycupgrass

Leptochloa filiformis--red spangletop

Oryza sativa--red rice

Panicum spp--e.g. witchgrass and fall-, browntop- and texas-panicum,wild proso millet

Poa annua--annual bluegrass

Setaria spp--e.g. giant foxtail, foxtail millet, yellow foxtail, bristlyfoxtail, green foxtail

Sorghum almum--sorghum almum

Sorshum bicolor--shattercane

Sorghum halepense--seedling johnson grass

Urochloa panicoides--liverseedgrass

Acanthospermum hispidum--bristly starbur

Amaranthus spp--e.g. pigweed, tumble pigweed; smooth pigweed, redrootpigweed, prostrate pigweed, waterhemp, spiny amaranth

Ambrosia artemisiifolia--common ragweed

Bidens pilosa--hairy beggarticks

Capsella bursa-pastoris--shepherdspurse

Chenopodium album--common lambsquarters

Cleome monophylla--spindlepod

Commelina spp--e.g. dayflower

Crotalaria sphaerocarpa

Datura stranionium--jimsonweed

Desmodium tortuosum--Florida beggarweed

Euphorbia nutans--nodding spurge

Euphorbia maculata--spotted spurge

Galinsoga paryiflora--smallflower galinsoga

Ipomea spp.--e.g. ivyleaf-, tall-, pitted morningglory

Lamium purpureum--purple deadnettle

Matricaria chamomilla--wild chamomile

Millugo verticillata--carpetweed

Papayer rhoeas--corn poppy

Polygonum spp.--e.g. smartweed, annual smatweed, wild buckwheat,prostrate knotweed

Portulaca oleracea--common purslane

Richardia scabra--Florida pusley

Schkuhria pinnata--dwarf marigold

Sida spinosa--prickly sida

Solanum spp.--e.g. black nightshade, E. black nightshade, hairynightshade, silverleaf nightshade

Stellaria media--common chickweed

Tagetes minuta--wild marigold (khaki weed)

Cyperus esculentis--yellow nutsedge

Cyperus iria--rice flatsedge

In addition the following weeds may also be controlled when employingappropriate mixing partners.

Abutilon theophrasti--velvetleaf

Hibiscus trionum--Venice mallow

Avena fatua--wild oats

Sinapis alba--white mustard

Xanthium strumarium--common cocklebur

Cassia obtusifolia--sicklepod

Apera spica-venti--windgrass

Campsis radicans--trumpet creeper

Rottboellia exaltata--itchgrass

Cynodon dactylon--bermudagrass

Lespedeza spp.--e.g. lespedezas

Trifolium spp.--e.g. clovers

Hippuris vulgaris--marestail

Asclepias spp.--e.g. milkweeds

Salvia spp.--e.g. lanceleaf sage

Salsola iberica--Russian thistle

Convolvulus arvensis--field bindweed

Cirsium arvense--Canada thistle

Proboscidea louisianica--devilsclaw

Senecio spp.--e.g. common groundsel

Chorispora tennela--blue mustard

Alopecurus myosuroides--blackgrass

Sisymbrium altissimum--tumble mustard

Caperionia palustris--texasweed

Crop selectivity will also usually depend upon choice of partners.Dimethenamid exhibits excellent selectivity in corn (maize), soybean andseveral other crops.

Examples of particular partners for co-application with dimethenamidinclude these selected from one or more of the types listed under a)through w) below.

a. benzoic acids, e.g. dicamba

b. picolinic acids and related compounds, e.g. picloram, triclopyr,fluroxpur, clopyralid

c. phenoxys, e.g. 2,4-D, 2,4-DB, triclopyr, MCPA, MCPP, 2,4-DP, MCPB

d. other chloracetamides, e.g. alachlor, acetochlor, metolachlor,diethatyl, propachlor, butachlor, pretilachlor, metazachlor,dimethachlor especially metolachlor, alachlor, acetochlor

e. amides, e.g. propanil, naptalam

f. carbamates, e.g. asulam

g. thiocarbamates, e.g. EPTC, butylate, cycloate, molinate, pebulate,thiobencarb, triallate, vernolate

h. nitriles, e.g. bromoxynil, ioxynil

i. ureas, e.g. diuron, thidiazuron, fluometuron, linuron, tebuthiuron,forchlorfenuron

j. triazines, e.g. atrazine, metribuzin, cyanazine, simazine, prometon,ametryn, prometryn, hexazinone

k. diphenyl ethers, e.g. acifluorfen, fomesafen, lactofen, oxyfluorfen

l. dinitroanilines, e.g. trifluralin, prodiarmine, benefin,ethalfluralin, isopropalin, oxyzalin, pendimethalin

m. sulfonylureas e.g. rimsulfuron, metsulfuron, nicosulfuron,triasulfuron, primisulfuron, bensulfuron, chlorimuron, chlorsulfuron,sulfometuron, thifensulfuron, tribenuron, ethametsulfuron,triflusulfuron, clopyrasufuron, pyrazasulfuron, prosulfuron(CGA-152005), halosulfuron, inetsulfuron-methyl, chlorimuron-ethyl;

n. inidazolinones, e.g. imazaquin, imazamethabenz, imazapyr,imazethapyr, imazmethapyr

o. cyclohexanediones, e.g. sethoxydim

p. aryloxyphenoxys, e.g. fluazifop

q. bipyridiliums, e.g. paraquat, diquat

r. pyridazinones, e.g. norflurazon

s. uracils, e.g. bromacil, terbacil

t. isoxazolones, e.g. clomazone

u. various, e.g. glyphosate, glufosinate, methazole, paclobutrazol,bentazon, desmedipham, phenmedipham, pyrazon, pyridate, amitrole,fluridone, DCPA, dithiopyr, pronamide, bensulide, napropamide, siduron,flumetsulam, sethoxydim, fluazifop, clethodim, diclofop-methyl,fenoxaprop-ethyl, haloxyfop-methyl, quizalofop, diclobenil, isoxabenz,oxadiazon, paclobutrazol, ethofumesate, quinclorac, difenzoquat,entothall, fosamine, DSMA, MSMA

v. Group 11a "others" as described above.

w. Group 11b "others" as described above.

Especially preferred partners among groups a) through w) are those ofgroups a), m), n), u) and v), i.e. the sulfonylureas and the triketonesand diones.

The co-application of the combination of dimethenamid and triketone(s)or dione(s) according to present invention is especially suitable incrops of monocotyledons, such as cereals, maize and rice. However,application in maize corps being infested with monocotyledonous anddicotyledonous weeds is most advantageous, as harmful effects againstthe crop plants are not enhanced. Both pre- and postemergenceapplication to the undesired weeds is possible with this preferredcombination. However, the preferred time point of application in maizeis after emergence of the maize seedlings.

Application rates for co-application of dimethenamid and a triketone ordione will of course vary depending upon climatic conditions, season,soil ecology, weeds to be combatted and the like, however, successfulresults can be obtained, e.g. in co-application with rates of thetriketone or dione which are significantly lower than recommended foruse thereof alone; e.g. 0.01 to 2 kg/ha, preferably 0.1 to 1 kg/ha.especially 0.1 to 0.6 kg/ha.

From this group, combinations are preferred wherein the triketone ordione is selected from4-4-chloro-2-nitrobenzoyl)-2,6,6-trimethyl-2H-1,2-oxazine-3,5-(4H,6H)dione, and sulcotrione, with sulcotrione being preferred.

The most preferred combination of this type is that of sulcotrione anddimethenamid. The mixture ratio will be determined according to thespecific soil, crop and climate condition of use. As an example theco-application rates will be in the range of 0.9 to 1.5 kg/ha ofdimethenamid and 0.15 to 0.45 kg/ha of sulcotrione. The ratio of theactive ingredient in the composition by weight of sulcotrione anddimethenamid is between 1:2 and 1:10.

For the co-application in a preferred 3-way mix comprising dimethenamidand a triketone or dione of group v), the third component is preferablyselected from the group j), i.e. the group of triazine herbicides. In atypical 3-way mix the triazine component will be present in a ratio of3:1 to 1:3 relative to the dimethenamnid content, with an excess ofdimethenamnid being preferred, i.e. a preferred ratio of 1:1 to 1:3,e.g. 1:1.5. The preferred triazine herbicide in this type of a 3-way mixis atrazine.

The co-application of the combination of dimethenamid andsulfonylurea(s) according to present invention is especially suitable incrops of monocotyledons, such as cereals, maize, sucar cane and rice.For example, application in sugar cane being infested withmonocotyledonous and dicotyledonous weeds is particularly advantageous,as the harmful effects against the crop plants are not enhanced, but theweeds are controlled very effectively. Both pre- and postemergenceapplications to the undesired weeds is possible with this combination.However, the preferred time point of application to sugar cane is afteremergence of the sugar cane seedlings, or transplantation of ratooncane.

In this use the application rates for co-application of dimethenamid anda sulfonylurea will of course vary depending upon climatic conditions,season, soil ecology, weeds to be combatted and the like, however,successfull results can be obtained, e.g. in co-application with ratesof the sulfonylurea which are significantly lower than the recommendeduse thereof alone; e.g. 1 to 150 g/ha, preferably 10 to 100 g/ha.

From this group the preferred combination for control of weeds in sugarcane is one wherein the sulfonylurea is chlorimuron. The mixture ratiowill be determinable according to the specific soil, crop and climatecondition of use. As an example the co-application rates will be in therange of 0.9 to 3.0 kg/ha of dimethenamid and 10 to 100 g/ha ofchlorimuron. For the combatting of cyperus spp. in sugar cane crop theymay be for example 2.0 to 3.0 kg/ha of dimethenamid and 50 to 90 g/ha ofchlorimuron. The ratio of active ingredient in the composition by weightof chlorimuron and dimethenamid is between 1:3000 and 1:20, preferably1:30 to 1:60, e.g. 1:34 or 1:38 or 1:45.

For the co-application in a preferred 3-way mix comprising dimethenamidand a sulfonylurea of group m), the third component is preferablyselected from the group i), i.e. the group of urea herbicides. In atypical 3-way mix the urea component will be present in a ratio of 2:1to 1:4, relative to the dimethenamid content, with an excess ofdimethenamid being preferred, i.e. a preferred ratio of 1:1 to 1:3, e.g.1:2. The preferred urea herbicide in this type of a 3-way mix is diuron.

It will be appreciated that mixtures of dimethenamid with more than oneherbicide e.g. 3-way mixes are also included within the purview of theinvention.

Examples of specific mixing partners can be selected for example fromthe following: paraquat (e.g. as GRAMOXONE® or GRAMOXONE®EXTRA),simazine (e.g. as PRINCEP®), glyphosate (e.g. as ROUNDUP®), glufosinate(e.g. as BASTA®); (Compound Group I).

Further examples of specific mixing partners can be selected from thefollowing: atrazine, cyanazine (e.g. as BLADEX® or together withatrazine as EXTRAZINE® or EXTRAZINE®II) terbutylazine, pendimethalin(e.g. as PROWL®), metribuzin, linuron (Compound Group II).

Further examples of specific mixing partners can be selected from thefollowing: nicosulfuron (e.g. as ACCENT®) rimsulfuron (e.g. as TITUS®)and primisulfuron (e.g. as BEACON®) (Compound Group III).

Further examples of specific mixing partners can be selected from thefollowing imazethapyr (e.g. as PURSUIT®), imazaquin (e.g. as SCEPTER®),chloramben, aclonifen (Compound Group IV).

Further examples of specific mixing partners can be selected from thefollowing:

dicamba (e.g. as BANVEL®, as CLARITY® (in DGA salt form) or togetherwith atrazine as MARKSMAN®).

Further examples of specific mixing partners can be selected fromsethoxydim (e.g. as POAST®), fluazifop (e.g. as FUSILADE®) (CompoundGroup V).

Further examples of specific mixing partners can be selected from thefollowing: sulcotrione (e.g. as MIKADO®) and4-(4-chloro-2-nitro-benzoyl)-2,6,6-trimethyl-2H-1,2-oxazine-3,5-(4H,6H)dione (Compound Group VI).

Further examples of specific mixing partners for 3-way mix aresulcotrione (e.g. as MIKADO®) and atrazine (e.g. as GESAPRIM®) (CompoundGroup VIa).

Further examples of specific mixing partners include chlorimuron (e.g.as CLASSIC® or in a 3-way mix together with diuron as FRONT®) (CompoundGroup VII).

According to the desired weed spectrum, time of application and the likeother specific herbicides listed within the groups a) through w) aboveare also particular examples of suitable mixing partners.

It has now also been found that very efficient control of grassy weedsin crops of sugar cane can also be with herbicides of the class ofchloracetamides in co-application with at least one herbicide of theclass of sulfonylurea herbicides (group m) optionally in the presence ofat least one herbicide of the class of the urea herbicide (group i).These components synergistically enhance the herbicidal effect of themixture. The chloroacetamides are widely used in agricultural practice.Preferred species of this group are inter alia Alachlor (LASSO®) whosechemical designation is2-chloro-2',6'-diethyl-N-methoxymethyl-acetanilide; Acetochlor(HARNESS®) whose chemical designation is2-chloro-N-(ethoxymethyl)-N-(2-ethyl-6-methylphenyl)acetarnide;Metolachlor (DUAL®) whose chemical designation is2-chloro-6'-ethyl-N-(2-methoxy-1-methylethyl)-aceto-toluidide;Metazachior (BUTISAN S®) whose chemical designation is2-chloro-N-(pyrazol-1-yl-methyl)acet-2',6'-xylidide; and dimethenamid(FRONTIER®) whose chemical designation is2-chloro-N(2,4-dimethyl-3-thienyl)-N-(2-methoxy-1-methylethyl)-acetamide.

Application rates of chloroacetamides for co-application will of coursevary depending upon climatic conditions, season, soil ecology, weeds tobe combatted and the like, however, successful results in sugar cane canbe obtained e.g. with rates of the chloroacetamide of 1 to 6 kg/ha,preferably 2 to 5.5 kg/ha in co-application with sulfonylurea and ureaherbicides. For example the specific application rates of thechloroacetamide component is 3to 6 kg/ha for Alachlor, e.g. 5.9 kg/ha,and 3 to 5 kg/ha for Metolachlor, e.g,. 4.3 kg/ha.

The mixture ratio of the chloroacetamide herbicide with the sulfonylureais generally between 20:1 and 300:1, preferably 20:1 to 100:1, e.g,.30:1 or 90:1. When a urea herbicide is co-applied with the mixture of achloroacetamide and a sulfonylurea it may preferably be applied in aratio of 1:1 to 1:5, relative to the chloroacetamide. e.g. 1:2 or 1:3 or1:4. The preferred chloroacetamides other than dimethenamid to beapplied in sugar cane with chlorimuron and diuron are acetochlor ormetolachlor.

Thus, another aspect of present invention is the control of grassy weedsin sugar cane with a combination of a chloroacetamide in associationwith a sulfonylurea and an urea herbicide. Specific preferredcombinations for this use are mixtures of dimethenamid, acetochior,alachlor or metolachlor with a combination of chlorimuron and diuron,e.g. in the commercially available 1:19 mixture FRONT®.

EXAMPLE 1

Active ingredients are weighed and dissolved in a stock solutionconsisting of acetone:deionized water, 1:1, and 0.5% adjuvant mixtureconsisting of surfactants SPAN® 20:TWEEN® 20:TWEEN® 85, 1:1:1. Dilutionsfrom this stock solution are performed to allow for preparation of spraysolutions consisting of single doses of individual or combined activeingredients. Each dose is applied simultaneously via a linear tracksprayer set to deliver 600 liters/ha spray volume to both the foliage ofthe selected weed seedling species, postemergence application, and thesurface of soil that had been previously sown with seeds, preemergenceapplication. The seedlings used are cultured to develop plants at thetwo- to early three-leaf stage. The stage of development of eachseedling at application time is recorded. After application, the treatedplants are transferred to the greenhouse and held until termination ofthe experiment within four weeks. Symptoms of injury are recorded twoand ten days after postemergence application and fourteen days afterpreemergence application. Visual percentage ratings of crop injury andweed control are taken ten and twenty-eight days after postemergenceapplication and fourteen and twenty-eight days after preemergenceapplication.

Co-application of dimethenamid with other specific active ingredientssuch as outlined above produces improved herbicidal effects comparedwith application of each active ingredient alone.

EXAMPLE 2

A field trial is carried out employing dimethenamid (as FRONTIER® 7.5EC) and nicosulfourn (as ACCENT® 75 WDG) in control of large crabgrassin corn. Application is as tankmix combination at early post-emergenceof the weeds (3 and 4 leaf stages). Application rates of a.i. are 1.5and 0.75 kg/ha for dimethenamid and 37.2 and 19.2 g/ha for nicosulfuron.Combined application of 0.75 kg/ha of dimethenamid and 19.2 g/ha ofnicosulfuron gave 85% control with negligible corn damage compared with35% for nicosulfuron applied alone at 19.2 g/ha and 72% for dimethenamidat a higher rate of 1.25 kg/ha. Combined application at the higher rateof dimethenamid with 37.2 g/ha of nicosulfuron gave an even moredramatic effect with 95% control compared with 72% for dimethenamid andonly 45% for nicosulfuron each alone.

Similar effects are noticed on combined treatment of broadleaf weedssuch as lambsquarters, prickly sida and morningglory employing 1.12kg/ha of dimethenamid (as FRONTIER®) and 0.071 kg/ha of imazethapyr (asPURSUIT®).

EXAMPLE 3

Small field units in a maize field, infested with echinochloa crus galliand solanum nigrum are sprayed with a tank-mix suspension ofdimethenamid and sulcotrione. The stage of the weeds is "full tillering"for echinochloa crus galli and "8-leaves stage" for solanum nigrum. Thelot size is 8 meters in length and 3 meters in width. The applicationrates are 1.1 kg/ha of dimethenamid and 0.15 kg/ha of sulcotrione. Sevendays after treatment the efficacy is evaluated, both as control of theweeds and as tolerance of the crop plants.

In this test the control of echinochloa was between 93 and 98% and thecontrol of solanum was between 91 and 93% in three repetitions, whilethe damage of the maize plants 7 was always below 10%.

EXAMPLE 4

Small field units in a maize field, infested with echinochloa crusgalli, solanum nigrum and chenopodium album are sprayed with a tank-mixsuspension of dimethenamid, sulcotrione and atrazine. The stage of theweeds is "full tillering" for echinochloa and "6-8 leaves stage" forsolanum and chenopodium. The lot size is 8 meters in length and 3 metersin broadth. The application rates are 1.08 kg/ha of dimethenamid. 150 or210 g/ha of sulcotrione and 750 g/ha of atrazine. 14 days aftertreatment the efficacy is evaluated. The results (in percentage control)were as follows:

    ______________________________________                               expected                               additive synergistic    Compound a.i./ha           effect   effect    ______________________________________                     Echinochloa                     control    Atrazine 1500    23        --    Dimethenamid/Atrazine 1080/750                     30        --    Sulcotrione/Atrazine 150/750                     26        --    Sulcotrione/Atrazine 210/750                     33        --    Dimethenamid/Sulcotrione/                     95        56       +39    Atrazine 1080/150/750    Dimethenamid/Sulcotrione/                     97        59       +42    Atrazine 1080/210/750                     Solanum/                     Cheno-                     podium    Atrazine 1500    16        --    Dimethenamid/Atrazine 1080/750                     36        --    Sulcotrione/Atrazine 150/750                     23        --    Sulcotrione/Atrazine 210/750                     53        --    Dimethenamid/Sulcotrione/                     97        53       +44    Atrazine 1080/150/750    Dimethenamid/Sulcotrione/                     100       89       +11    Atrazine 1080/210/750    ______________________________________

The synergistic effect is clearly visible at the lower rates ofsulcotrione, resulting in a nearly doubled degree of control, comparedto the expected additive efficacies. For the higher rates ofsulcotrione, (>300 g/ha) only the additive effect remains visible sincethe total control is 100%.

EXAMPLE 5

A field trial is carried out on plots (2×20 m) planted with sugar caneand infested with cyperus rotundus in the first or second growing stageand sprayed with a backpack sprayer in different concentrations in atank mix. The amount of liquid spray broth is 400 l/ha. The applicationrates are 2.7 kg/ha of dimethenamid with 60 g/ha of chlorimuron or with1.6 kg/ha of a fixed ratio mixture of chlorimuron and diuron (1:19)which is commercially available as FRONT®. Visual evaluation is done 30or 60 days after treatment (DAT) in percentage of control. The expectedadditive effect value is calculated according to the method of Colby:

    ______________________________________    Compound a.i./ha                  Cyperus    expected   synergistic    conditions    Control (DAT)                             additive effect                                        effect    ______________________________________    light to medium soil    Dimethenamid 2.7 kg                  19 (60 DAT)                             --    Chlorimuron/Diuron                  45 (60 DAT)                             --    1.6 kg    Dimethenamid/Chlori-                  76 (60 DAT)                             55         +21    muron/Diuron 2.7 + 1.6 kg    heavy soil    Dimethenamid 2.7 kg                  10 (60 DAT)                             --    Chlorimuron/Diuron                  37 (60 DAT)                             --    1.6 kg    Dimethenamid/Chlori-                  74 (60 DAT)                             43         +31    muron/Diuron 2.7 + 1.6 kg    light to medium soil    Dimethenamid 2.25 kg                  23 (30 DAT)                             --    Chlorimuron/Diuron                  48 (30 DAT)                             --    1.2 kg    Dimethenamid/Chlori-                  80 (30 DAT)                             60         +20    muron/Diuron    2.25 + 1.2 kg    light to medium soil    Dimethenamid 2.7 kg                  27 (30 DAT)                             --    Chlorimuron/Diuron                  48 (30 DAT)                             --    1.2 kg    Dimethenamid/Chlori-                  88 (30 DAT)                             62         +26    muron/Diuron 2.7 + 1.2 kg    light to medium soil    Dimethenamid 2.7 kg                  27 (30 DAT)                             --    Chlorimuron 0.06 kg                  58 (30 DAT)                             --    Dimethenamid/Chlori-                  93 (30 DAT)                             69         +24    muron 2.7 + 0.06 kg    ______________________________________

The achieved results indicate that synergistic effects are obtained withthe 2-way mix (dimethenamid/chlorimuron), as well as with the 3-way mix(dimethenamid/chlorimuron/diuron).

EXAMPLE 6

In the procedure as set out in Example 5, tank mixtures of 5.7 kg/ha ofalachlor or 4.3 kg/ha of metolachlor with 1.2 kg/ha of the fixed ratiomixture of chlorimuron and diuron (1:19; commercial FRONT®) whereapplied to a sugar cane field. The results were as follows:

    ______________________________________    Compound a.i./ha                  Cyperus    expected   synergistic    conditions    Control (DAT)                             additive effect                                        effect    ______________________________________    light to medium soil    Alachlor 5.4 kg                  30 (30 DAT)                             --    Chlorimuron/Diuron                  48 (30 DAT)                             --    1.2 kg    Alachlor/Chlorimuron/                  85 (30 DAT)                             64         +21    Diuron 5.4 + 1.2 kg    light to medium soil    Metolachlor 4.3 kg                  23 (30 DAT)                             --    Chlorimuron/Diuron                  48 (30 DAT)                             --    1.2 kg    Metolachlor/Chlorimuron/                  89 (30 DAT)                             60         +29    Diuron 4.3 + 1.2 kg    ______________________________________

What is claimed is:
 1. A herbicidal composition comprising aherbicidally effective amount of dimethenamid, bentazon, and anagriculturally acceptable carrier.
 2. The composition of claim 1 whereinthe amount of dimethenamid is such that it can be applied at a rate from0.1 to 3.0 kg/ha.
 3. The composition of claim 1 wherein the amount ofdimethenamid is such that it can be applied at a rate from 0.25 to 1.5kg/ha.
 4. The composition of claim 1 wherein the amount of bentazon issuch that it can be applied at a rate from 0.1 to 3.0 kg/ha.
 5. A methodof controlling undesired plant growth in the presence of a cropcomprising applying postemergence to the locus of a broadleaf weed, aherbicidally effective aggregate amount of dimethenamid and bentazonwherein the application rate of dimethenamid is from 0.1 to 3.0 kg/ha.6. The method of claim 5, wherein the application rate of the bentazonis from 0.1 to 3.0 kg/ha.
 7. The method of claim 5, wherein theapplication rate of dimethenamid is from 0.25 to 1.5 kg/ha.
 8. Themethod of claim 5 wherein said applying step comprises co-applyingdimethenamid and bentazon in a tank mix.
 9. The method of claim 5wherein said applying step comprises applying the herbicides to thelocus of a broadleaf weed in the presence of a corn or soybean crop. 10.The method of claim 5 wherein said applying step comprises applying theherbicides simultaneously to the locus of a broadleaf weed.
 11. Themethod of claim 5 wherein said applying step comprises applying theherbicides sequentially to the locus of a broadleaf weed.
 12. A methodof potentiating the herbicidal effect of bentazon comprising combiningbentazon with a potentiating effective amount of dimethenamid to producea herbicidally effective composition.